SE 1.04Brown Stair
The child grades ten brown prisms, all 20 cm long, from thickest (10 cm) to thinnest (1 cm).
Presentation
- 1
Invite the child and unroll a rug near the stair.
- 2
Show how to carry the thick prisms: one hand under each end, held against the body. Thin prisms may be carried in one hand, gripped from above.
- 3
Bring the prisms to the rug one at a time and place them at random.
- 4
Choose the thickest prism and place it at the top of the rug, then find the next thickest and place it below, touching, with the left ends aligned.
- 5
Continue until all ten form a stair.
- 6
Run your hand down the steps from thickest to thinnest.
- 7
Take the smallest pink tower cube and slide it along each step to show every step is the same height.
- 8
Return the prisms to the shelf one at a time.
Extensions, easiest to hardest
- Build the stair with the ends aligned on the right side.
- Build the stair standing on end or in other arrangements.
- Grade the prisms with eyes closed, feeling the ends to compare thickness.
- Bring the prisms from a distance one at a time in order.
Control of error
A prism out of order leaves a step that is taller or shorter than the others; the smallest Pink Tower cube will not sit evenly on that step.
Ready to move on when the child…
- Builds the stair in correct order without help
- Aligns the ends of the prisms
- Checks steps with the smallest cube or by eye and corrects mistakes